Currently, approaches are being made worldwide, targeted at a low-carbon society against a backdrop of global warming and crude oil depletion problems. Among such efforts, attention is being focused on energy production methods utilizing biomass; in particular it is bioethanol as an energy alternative to gasoline that is gaining a spotlight. However, because the production of bioethanol uses as a feedstock starch and carbohydrates which are used as food, their conversion to bioethanol production is considered limited from standpoints such as a rise in grain prices and the food crises.
This has led to studies of methods for producing ethanol using wood-based biomass feedstock which does not compete with food, whereby cellulose is subjected to a chemical treatment and use of microorganism's enzymes, and like. However, there also exists a substantial obstacle of production costs in the production of alcohol for fuel using the wood-based biomass, making it currently difficult to use it as for-fuel alcohol.
On another front, studies have been ongoing to utilize wood-based biomass for food supply. For example, Patent Reference 1 is for producing a fertilizer by fermenting the sheaths of bamboo shoot or young bamboo and Patent Reference 2 for producing a health food ingredient containing theanine and the like. However, Patent Reference 1 is exclusively for producing a fertilizer, and not possible to make food. Further, Patent Reference 2 uses anaerobic bacteria making it unfit for seasonings and beverages.
Patent Reference 3 proposes a method for producing bamboo vinegar as a health food free from carcinogens such as benzpyrene or substances hazardous to the human body, which are found in a bamboo vinegar obtained from distillation of smoke that accompanies the conventional bamboo charcoal production. However, the distillation thereof at low temperature under reduced pressure ends up taking as long as 5 to 15 days and the product contains many impurities. Further, Patent Reference 4 proposes a method of an alcoholic fermentation using koji fungus (Aspergillus oryz) but it uses grain as feedstock so that the same procedure without change cannot be adapted for production of a fermentation product of trees such as bamboo containing antimicrobials.